Prior art methods of preparing batches of dry colorant include manually measuring and mixing the batch of colorant from three different bags or containers each containing one of the primary colors of pigment. This is a labor-intensive process prone to human error during the measuring and mixing. The prior art process may also result in workplace injury, as bulk colorant is provided in large, heavy amounts. Others have attempted to maintain an inventory of pre-batched colors. This requires the user to maintain a large inventory of batched colorants, if the customer desires to have the different colored colorants immediately in stock.
Dry colorant is difficult to handle and/or transfer, as it tends to clump and stick together forming cakes and lumps. The dry colorant will coat and adhere to packaging and handling equipment. The dry colorant often forms “bridges” in the prior art handling apparatus and systems that clog the apparatus with dry colorant resulting in a loss in production.
As such, dry colorant is often processed into a granule that has improved transfer and handling characteristics as compared to the dry colorant. The granules generally comprise encapsulated dry pigments. The granules have a much larger size than the dry pigments and often tend to have a roughly spherical shape. The granules also have a more consistent and uniform shape. These features of granules improve their transfer and handling characteristics.
The granules may be produced by forming a slurry of the dry colorant with a binder. The slurry is then spray dried to form the granule. The binder may include a ligand based binder. The granules may also be produced using a compacting method, where the dry colorant is dampened with water and then compacted with the binder in a compacting machine.
The individual granules have a much larger size than the individual dry colorant particles. The granules typically have a size of hundreds of micrometers or larger. Unfortunately, granules of dry powder are not suitable for mortar applications since the granules do not break down or disperse sufficiently during the mixing of the mortar, and the resulting mortar will have streaks and other undesirable areas of highly-concentrated color. These streaks and areas may be unacceptable for certain applications. As such, mortar generally requires the use of the dry powder, and not granules, in order to color the mortar.